1. Field of the Invention
The present invention relates to an implantable electrostimulation device for a heart, in particular an implantable cardioverter/defibrillator.
2. Description of the Related Art
Implantable cardiac pacemakers and implantable cardioverters/defibrillators have reached a high level of development. The devices must operate reliably over years, since they are only accessible in the implanted state via an operation. This sets limits to the complexity of the devices. However, cardiac pacemakers and defibrillators are to be capable of detecting pathological states of the heart to be treated both with high sensitivity and also with high specificity, so that a state in need of treatment does not remain unrecognized and, in addition, unnecessary or incorrect treatment is avoided as much as possible. In connection with implantable cardioverters/defibrillators (ICDs), the difference between tachycardias which have their origin in the ventricle (ventricular tachycardias), and supraventricular tachycardias, which have their origin in the atrium, for example, is cited here.
Furthermore, the problems still exists of being able to recognize successful treatment as reliably as possible, in order to otherwise be able to adapt the treatment. In the simplest case, this relates to setting the strength of a stimulation pulse. This is to be dimensioned precisely so that the cardiac tissue (myocardium) of the stimulated heart chamber—i.e., atrium or ventricle—responds to the stimulation pulse and contracts as a result. However, stimulation pulses which are too strong are to be avoided in order to avoid unnecessary energy consumption, because the energy must be taken from a battery whose exhaustion makes an operation and replacement of the stimulation device necessary. Precisely in biventricular pacemakers for resynchronization therapy (CRT: cardiac resynchronization therapy), detecting the success of stimulation (capture detection) still causes problems, particularly in the left ventricle.
An array of individual solutions to the problems indicated here are known.